Here is what I came up with. I appreciate the advice posted here in March and would appreciate any comments or criticisms, especially from those who have shot game with any of these bullets.
CAUTION: These are my loads in my rifle using my chronograph. They may be dangerous in yours so work up slowly.
Elephant bullets: The 450 grain North Fork was highly recommended. I preferred the Barnes 450 grain monolithic. Both have flat meplats, like Elmer Kieth revolver bullets, which are said to penetrate better than a round nosed bullet. The Barnes meplat is 7mm in diameter and the North Fork 8mm, a small difference. But the North Fork is much harder to crimp because the crimping grooves are so small and close together. The North Fork may group a little tighter but not enough to bother with. Velocity was about the same.
450 grain vs. 500 grain Barnes solids: The nose is identical. Many people recommend the 450, which I decided to use because the recoil is noticeably less. Some say the 450 penetrates deeper because it yaws less at close range. However, with AA2230 I can get adequate velocity with either in my Model 70.
Powders: AA2230 was recommended for 500 grain bullets and H4895 for 450 grain bullets. I concluded that AA2230 is better for all bullets. It's denser and you can get more in the case. Also you need less because it is a little faster burning. For instance, even with the 350 grain Hornady bullet, 80 grains of H4895 got me 2370 fps vs. 77 grains of AA2230 yielding 2500. I will use no other powder unless someone thinks AA2230 is very temperature sensitive.
These loads seemed very good and non-maximum. All grouped 2" to 2.5" at 100 yards (and my bench technique is not so good with this rifle) except the Hornady seemed a little worse.
72-AA2230-500 Barnes solid 2220 fps for elephant
73-AA2230-450 Barnes solid 2320 fps for elephant
73-AA2230-450 Barnes TSX 2275 fps for non-dangerous stuff
77-AA2230-350 Hornady SP 2510 fps for non-dangerous stuff
All but the Hornady load comfortably exceed 5000 foot pounds. I don't know whether to take the 350 Hornady or the 450 TSX for my expanding bullet load. All four loads shoot to about the same aim point at 100 yards but I have not yet shot them at 200. The 350 grain bullet's higher velocity might let it drop less, but its awful ballistic coefficient might give the advantage to the pointed TSX.
Bench shooting technique: I always wear a heavy leather padded High-power coat made by Creedmore. In this case, I folded up a towel and placed it over my right shoulder inside the coat as well. I grasp the rifle firmly with both hands. This makes bench shooting tolerable. Recoil is less obnoxious than my 300 Weatherby Ultra-Lightweight, which has a nasty habit of cutting my finger with the trigger guard if I'm not careful.
Don't trust loading manuals: At least two prominent manuals list 78 grains of AA2230 as the maximum load for 500 grain bullets. So I loaded a few with 77 grains. The first one chronographed 2376 fps but, funny thing, the bolt handle was hard to lift! I shot no more of these. BTW: If I take the Hornady load on safari, I will probably cut it to 76 grains, just on general principles.
A sensitivity test: I ran this with H4895 and 450 grain Barnes solids. One shot was fired at each charge weight. I then smoothed the data with a second order polynomial to get a smooth average. Charges and velocities were:
72 2210
73 2220
74 2230
75 2250
76 2290
I suspect this indicates sharp pressure rises after 74 grains and I would use no heavier charge.
